Thermodynamic Driving Force in the Spontaneous Formation of Inorganic Nanoparticle Solutions

Lance M. Wheeler, Nicolaas J. Kramer, Uwe R. Kortshagen

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Nanoparticles are the bridge between the molecular and the macroscopic worlds. The growing number of commercial applications for nanoparticles spans from consumer products to new frontiers of medicine and next-generation optoelectronic technology. They are most commonly deployed in the form of a colloid, or "ink", which are formulated with solvents, surfactants, and electrolytes to kinetically prevent the solid particulate phase from reaching the thermodynamically favored state of separate solid and liquid phases. In this work, we theoretically determine the thermodynamic requirements for forming a single-phase solution of spherical particles and engineer a model system to experimentally demonstrate the spontaneous formation of solutions composed of only solvent and bare inorganic nanoparticles. We show molecular interactions at the nanoparticle interface are the driving force in high-concentration nanoparticle solutions. The work establishes a regime where inorganic nanoparticles behave as molecular solutes as opposed to kinetically stable colloids, which has far-reaching implications for the future design and deployment of nanomaterial technologies.

Original languageEnglish (US)
Pages (from-to)1888-1895
Number of pages8
JournalNano letters
Issue number3
StatePublished - Mar 14 2018

Bibliographical note

Funding Information:
The work of L.M.W. was supported by the University of Minnesota Doctoral Dissertation Fellowship. L.M.W. and U.R.K. were supported by the DOE Energy Frontier Research Center for Advanced Solar Photophysics. Part of this work was carried out in the College of Science and Engineering Characterization Facility, University of Minnesota, which has received capital equipment funding from the NSF through the University of Minnesota Materials Research Science and Engineering Center (MRSEC, grant DMR-1420013). The authors thank Chris Hogan (University of Minnesota), Chris Sorensen (Kansas State University), Nicholas Anderson (National Renewable Energy Laboratory), and Vincent Wheeler (Australian National University) for helpful and stimulating discussion.

Publisher Copyright:
© 2018 American Chemical Society.


  • colloidal stability
  • ligand-free
  • quantum dot
  • semiconductor nanocrystal
  • Silicon

MRSEC Support

  • Shared

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't


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